Diodes Incorporated AL1678-10BS7-13

Overview

AL1678-10BS7-13 from Diodes Incorporated is a universal-input (85–277 VAC), boundary-conduction-mode (BCM) buck LED driver IC with integrated 500 V/1.0 A MOSFET in SO-7 package. It delivers ±3% constant current accuracy, >90% efficiency, and supports retrofit LED lamps requiring low-BOM, non-isolated constant-current operation at up to 10 W output power.

For engineers reviewing the AL1678-10BS7-13 datasheet, AL1678-10BS7-13 pinout, AL1678-10BS7-13 application, or AL1678-10BS7-13 equivalent, key selection criteria include its internal 500 V MOSFET rating, 0.4 V current-sense reference, thermal fold-back at +140°C, UVLO startup threshold of 14.5 V, and SO-7 thermal performance (θ_JA = 190°C/W).

Technical Context

The AL1678-10BS7-13 implements valley-switching peak-current control in BCM to minimize EMI and switching losses. Its integrated 500 V MOSFET eliminates external high-voltage switches, while the 0.4 V CS reference and 0.46 V ROVP reference enable precise current regulation and open-load voltage clamping.

It features adaptive t_ON/t_OFF timing control (t_{ON_MIN} = 400 ns, t_{ON_MAX} = 35 µs, t_{OFF_MIN} = 6 µs, t_{OFF_MAX} = 200 µs) and self-regulating thermal fold-back that linearly reduces output current above +140°C - distinct from latch-type OTP activation at +170°C.

Key Specifications

Pinout & Package

AL1678-10BS7-13 is housed in a 7-pin SOIC (SO-7) package with exposed drain pad for thermal enhancement. Pin 7 (Drain) connects directly to the internal 500 V MOSFET's drain terminal and must be routed to a thermally robust copper area.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck LED driver applications.

Compared with AL1678-20BS7-13 and AL1678-08BS7-13, the AL1678-10BS7-13 provides optimal balance of thermal capability (0.65 W dissipation), current capacity (1.0 A), and R_DS(on) (10 Ω typ) for 8–10 W LED drivers - avoiding overdesign or insufficient margin in mid-range commercial lighting.

Availability

AL1678-10BS7-13 is available at Aetrix Electronics and suitable for retrofit LED lamps, high-voltage DC-DC LED drivers, and general-purpose constant-current sources requiring stable component supply and legacy design continuity.

Supply support for AL1678-10BS7-13 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Diodes Incorporated is a global semiconductor company specializing in discrete, analog, and mixed-signal ICs for power management, signal integrity, and connectivity applications.

The AL1678 series belongs to Diodes' AC-DC LED driver product line, designed specifically for cost-sensitive, non-isolated buck topologies in residential and commercial lighting where high efficiency, regulatory compliance, and minimal external components are critical.

FAQ

Is AL1678-10BS7-13 still in active production?

No - Diodes Incorporated has officially discontinued the AL1678-10BS7-13 and all variants in the AL1678 family (DS37637 Rev. 3–4, November 2020). It is marked "OBSOLETE – PART DISCONTINUED" in the official datasheet. Aetrix Electronics maintains limited legacy stock for design continuity and last-time buy support, but no new manufacturing is planned.

What is the maximum recommended output power for AL1678-10BS7-13?

The datasheet specifies ≤10 W maximum output power for AL1678-10BS7-13 under standard conditions (T_A ≤ +50°C, SO-7 package, no forced airflow). This limit arises from thermal constraints: 0.65 W max power dissipation, 190°C/W θ_JA, and 1.0 A MOSFET current rating. Higher power requires derating or enhanced heatsinking per Figure 6 in DS37637.

Can AL1678-10BS7-13 operate without an auxiliary winding?

Yes - the AL1678-10BS7-13 uses an internal valley-detection circuit to sense t_OFF time and does not require an auxiliary winding for VCC supply or demagnetization detection. VCC is charged directly from the rectified AC line via a resistive dropper and storage capacitor, enabling true single-winding inductor operation.

How does thermal fold-back differ from over-temperature protection (OTP) in this device?

Thermal fold-back activates at +140°C junction temperature and linearly reduces output current to lower power dissipation, allowing continued operation at reduced brightness. OTP triggers at +170°C and forces a latched shutdown - the device remains off until AC power is cycled. Fold-back prevents thermal runaway; OTP is a final safety cutoff.